The loss of reproductive cyclicity in aging human females is characterized by a loss in ovarian function and a decline in estrogen and progesterone secretion. There is a corresponding rise in follicle- stimulating hormone and luteinizing hormone in peripheral plasma, suggesting a release of the hypothalamic-pituitary axis from the inhibitory feedback effects of ovarian steroids. It is not known whether this rise in plasma gonadotropins is due to an increase in luteinizing hormone releasing hormone (LHRH) secretion from the hypothalamus or a change in anterior pituitary responsiveness to LHRH. We propose in Pilot 3 to map the distribution of neurons that contain LHRH mRNA in human female hypothalamus. We hope to correlate the dramatic changes in anterior pituitary hormone release in menopause to the levels of hypothalamic mRNA for LHRH. This investigation will lay the groundwork for studying the aging human hypothalamus by examining a well- characterized system with a dramatic functional alteration.